Numerical simulation of wind load characteristics and vortex-induced vibration lock-in risk of multi-equipment smart traffic poles

Abstract

Adding multiple devices to traffic poles completely changes their aerodynamic characteristics, creating dangerous wind-induced vibration issues that current design codes don’t cover. We built 1:1 models of a plain traffic pole and a fully equipped smart pole, then ran comparative CFD simulations using SST k-ω and SIMPLEC. The results were striking: at 0° wind, the smart pole had a 65.4% higher drag coefficient and a 17x larger RMS lift coefficient than the plain pole. At 10 m/s (Re ≈ 1.37 × 106), we measured a Strouhal number of ∼0.12 and a vortex shedding frequency of 0.5988 Hz. This gives a frequency ratio of 0.784 relative to the first natural frequency (0.7638 Hz), just below the 0.8 lock-in threshold. Most critically, asymmetric equipment mounting splits the first-order bending mode into two closely spaced modes: 0.7638 Hz and 0.79681 Hz (4.3% difference). Their lock-in wind speed ranges overlap by 4.66 m/s, covering an unprecedented 91.4% of the first mode’s entire lock-in interval.